Abstract

The two-spotted spider mite, Tetranychus urticae Koch, is very polyphagous and considered a serious pest worldwide. The use of relatively resistant crop cultivars may limit the negative effects of this pest; we therefore compared population growth parameters of T. urticae reared on five commonly grown bean cultivars in Iran (Derakhshan, G14, Sayyad, D81, and Talash). The life table parameters were estimated at 25±1oC, 60±10% RH, and a photoperiod of 18:6 h (L:D). Egg hatchability, development time and survival to adult stage were similar among cultivars, but we detected significant variation in fecundity and longevity, resulting in large differences for population growth parameters like the intrinsic rate of natural increase (rm), net reproductive rate (R0), finite rate of increase (λ) and doubling time (DT). Sayyad was the most favourable host for two-spotted spider mites with rm 0.295 (offspring/female/day), followed by G14 (0.261), D81 (0.244) and Derakhshan (0.238). Theslowest population growth was observed on the Talash variety with rm 0.214. These findings indicate that the choice of bean variety will affect how fast spider mite populations reach damaging levels in a culture.